How to zip files (and when you shouldn't bother)

To zip files, select them and use the built-in compress command: Compress to > ZIP File in Windows 11 File Explorer, Compress in the Finder's right-click menu on a Mac, and More > Compress in the iPhone Files app. To unzip, double-click (or tap) the archive, or choose Extract All on Windows. Zipping is worth doing when you want to bundle many files or a folder into one attachment, or when the files are documents, spreadsheets or text that shrink well. It does little for photos and videos, which are already compressed. If you need a password, the built-in tools will not help; use 7-Zip with AES-256 encryption instead.

Windows 11

Create a zip

1. In File Explorer, select the files or folder.
2. Right-click and choose Compress to > ZIP File. On older Windows 11 builds without that entry, use Show more options > Send to > Compressed (zipped) folder, which still works.
3. Type a name for the archive and press Enter. It appears in the same folder.

You can drag more files onto an existing zip to add them.

7z and TAR are now built in

Windows 11 version 23H2 added the ability to open RAR, 7z, TAR and other formats in File Explorer. Version 24H2 added the ability to create 7z and TAR archives too. Right-click and choose Compress to, then 7z File or TAR File, or pick Additional options to open a wizard where you choose the format (zip, 7zip or tar), the compression method (for example LZMA2 for 7z, or Gzip, BZIP2, xz or Zstandard for tar) and the compression level.

Unzip

• Double-click the archive to browse it like a folder, then drag out what you need.
• To extract everything, right-click the archive and choose Extract All, then pick a destination.

macOS

1. In the Finder, select one or more items.
2. Control-click (or right-click) and choose Compress. A single item becomes Name.zip; several items become Archive.zip.
3. To unzip, double-click the zip file. The contents appear next to it in the same folder.

Archives made on a Mac open normally on Windows, but they include hidden __MACOSX folders and .DS_Store files that Windows users will see as clutter. They are harmless and can be deleted. For moving files between the two systems more generally, see sending files from Mac to Windows.

The Finder cannot add a password. The Terminal command zip -er archive.zip folder can, but it uses the old ZipCrypto scheme, which is weak. Use a tool that supports AES-256 (several free ones are in the Mac App Store, and the command-line 7zz build of 7-Zip runs on macOS) when the contents are sensitive.

iPhone and iPad (Files app)

1. Open the Files app and go to the folder, for example On My iPhone or iCloud Drive.
2. Tap the More button (three dots), then Select, and choose the items.
3. Tap More in the lower-right corner, then Compress. One item keeps its name; several become Archive.zip.
4. To open a zip, just tap it. Files creates a folder with the contents next to it.

Photos must be saved to Files first (Share > Save to Files) before you can zip them.

Android (Files by Google)

1. Open Files by Google and browse to the zip file.
2. Tap it to see the contents, then tap Extract. Tick Delete ZIP file if you do not need the archive afterwards.
3. Tap Done. The extracted files appear in the same folder.

Files by Google only extracts .zip, not 7z or RAR. Newer versions also offer a Compress option in the three-dot menu next to a file or folder; if you do not see it, update the app, or use your phone maker's file manager (Samsung My Files, for example, has its own compress option) or a third-party archiver.

When zipping helps, and when it doesn't

Zip compression works by finding repeated patterns and storing them once. Text, spreadsheets, CSV and log files, source code and uncompressed formats like BMP, WAV and many raw database exports are full of repetition and can shrink dramatically. Formats that are already compressed have had that redundancy squeezed out, so a zip just wraps them with a few bytes of overhead.

Bundling is a real benefit even without compression. Many upload forms and email clients cannot attach a folder at all (Apple's Mail Drop, for example, requires folders to be compressed first), and moving one large file is usually faster and more reliable than moving thousands of tiny ones. If you are trying to get under an email attachment limit with a video, though, zipping will not get you there.

Password-protected archives with 7-Zip

Windows' own archive support cannot create or open encrypted archives; Microsoft's help page says so directly and points to tools like 7-Zip or WinRAR. 7-Zip is free, open source and supports AES-256 encryption for both 7z and zip formats.

1. Install 7-Zip from 7-zip.org.
2. Select the files, right-click and choose 7-Zip > Add to archive. On Windows 11 the 7-Zip entry may be under Show more options.
3. Set Archive format to 7z (strongest) or zip (most compatible).
4. Under Encryption, enter a password twice and set Encryption method to AES-256. For zip, 7-Zip also offers ZipCrypto; avoid it, as it is easy to break.
5. For 7z, tick Encrypt file names so nobody can see what is inside without the password.
6. Click OK.

Two caveats. First, an AES-encrypted zip will not open in Windows File Explorer or in the macOS Archive Utility, so the recipient needs 7-Zip or another tool that supports AES. Second, the encryption is only as strong as the password: use a long passphrase, and send it by a different route from the file itself.

Common problems and their fixes

• "The compressed (zipped) folder is invalid" on Windows. The download was usually cut short, or the archive uses a feature the built-in tool does not support, such as AES encryption. Download it again and compare the file size with what the sender reports, or open it with 7-Zip.
• File names turn into gibberish. Older zip tools stored names in a local character set rather than Unicode, so accented or non-Latin names can break when the archive moves between systems. 7z archives and recent zip tools store Unicode names, which avoids this.
• Extraction fails partway with a path error. Deeply nested folders can exceed Windows' traditional 260-character path limit. Extract to a short location such as C:\x, or rename long folders before zipping.
• The recipient cannot open a .7z or .tar.gz. iPhone's Files app and Files by Google handle only zip, and Windows before 23H2 handles only zip. Send a zip unless you know they have a suitable tool.
• Email or a security gateway blocks the archive. Some organisations strip zip attachments or reject encrypted ones because their scanners cannot see inside. Ask what they accept, or share via a link.

Splitting a large archive

If a file is too big for a single upload or attachment, 7-Zip can cut the archive into fixed-size parts. In the Add to archive dialog, fill in Split to volumes, bytes with a size such as 20M or pick a preset. You get files named archive.7z.001, archive.7z.002 and so on. The recipient puts all parts in one folder and opens the .001 file with 7-Zip, which rejoins them.

Splitting is useful when a service has a hard per-file cap. It is clumsy when you could simply send one file another way: every part must arrive intact, and the recipient needs compatible software. If both of you are online at the same time, a direct transfer such as TransferFiles.net sends the whole file in one go from browser to browser, with no size limit set by us, so you can skip the splitting step entirely. For sending work to clients, our guide to delivering large files to clients compares the options.

Sources

• Microsoft Support: Zip and unzip files
• Pureinfotech: Create 7z and TAR files on Windows 11
• Apple Support: Zip and unzip files and folders on Mac
• Apple Support: Create or open ZIP files on your iPhone or iPad
• Google: Unzip your files (Files by Google)
• 7-Zip home page and 7z format
• Apple Support: Mail Drop limits